1. Field of the Invention
This invention generally relates to systems and methods to treat obstructive sleep apnea (OSA), more particularly to minimally invasive solutions to prevent collapse of the upper pharyngeal airway.
2. Related Art
OSA is caused by a blockage of the airway, which usually occurs when the soft tissue in the throat collapses and closes during sleep. According to the National Institutes of Health, OSA affects more than twelve million Americans. During each apnea event, the brain briefly arouses the sufferer in order to initiate the resumption of breathing. This type of sleep, however, is extremely fragmented and of poor quality. When left untreated, OSA may result in high blood pressure, cardiovascular disease, weight gain, impotency, headaches, memory problems, job impairment, and motor vehicle crashes. Despite the seriousness of OSA, a general lack of awareness among the public and healthcare professionals results in the vast majority of OSA sufferers remaining undiagnosed and untreated.
One non-surgical method available to treat OSA, commonly referred to as continuous positive airway pressure (CPAP), delivers air into a patient's airway through a specially designed nasal mask or pillow. The flow of air creates positive pressure when the patient inhales to keep the airway open. CPAP is considered by many to be an effective non-surgical treatment for the alleviation of snoring and obstructive sleep apnea, however, patients complain about discomfort caused by the mask and hoses, including bloating, nasal drying, and dry eyes. As a result, patient compliance for CPAP is only about 40%.
Surgical treatments have also been used to treat OSA. One such treatment is referred to as uvulopalatopharyngoplasty, which involves removing about 2 cm of the trailing edge of the soft palate to reduce the soft palate's ability to flutter between the tongue and the pharyngeal wall. Another procedure uses a surgical laser to create scar tissue on the surface of the soft palate, which reduces the flexibility of the soft palate for reducing snoring and/or closing of the air passage. Yet another procedure, commonly referred to as cautery-assisted palatal stiffening operation (CAPSO), is an office-based procedure performed under local anesthesia whereby a midline strip of soft palate mucosa is removed, and the wound is allowed to heal whereupon the flaccid palate is stiffened.
Surgical procedures such as those mentioned above continue to have challenges. More specifically, the area of tissue that is surgically treated (i.e., removal of palatal tissue or scarring of palatal tissue) is often larger than is necessary to treat the patient's condition. In addition, the above-mentioned surgical procedures are often painful with extended, uncomfortable healing periods. For example, scar tissue on the soft palate may be a cause of continuing irritation to the patient. Furthermore, the above procedures are not reversible in the event of adverse side effects.
Another implant system, sold under the trademark REPOSE™ by InfluENT of Concord, N.H., uses a titanium screw that is inserted into the posterior aspect of the mandible at the floor of the mouth. The screw acts as an anchor. A loop of suture is passed through the tongue base and attached to the mandibular bone screw. The REPOSE™ procedure achieves a suspension or hammock of the tongue base making it less likely for the base of the tongue to prolapse into the patient's airway during sleep. Due to the high activity of the tongue during wakefulness, however, the suture component of this device may act as a cutting element within the tongue, causing device trans-location and ultimately a loss of efficacy of the procedure thereby requiring subsequent removal.
An additional tongue suspension device developed by ASPIRE Medical is named the ADVANCE System. It is similar to the REPOSE suture suspension system for the tongue base in that it utilizes a bone screw in the mandible as an anchor, but has the advantage of being adjustable. The device further utilizes a flexible shape memory soft tissue anchor within the tongue that is shaped similar to a grappling hook, to engage the tissue within the tongue base. The soft tissue anchor is placed through a small incision in the submental region of the patient's head and the suture is attached to a spool-like component attached to the mandible. Two to four weeks after healing, a small incision is made under the chin and a screw is turned to tighten the suture, thus pulling the device forward. While the device provides a simplified installation technique from within the sterile space, the anchors may suffer from device fracture and failure due to loading within the tongue musculature.
A further system is disclosed in US 2008/0208265, Frazier, et al., entitled “System and Method for Percutaneous Palate Remodeling.” This publication discloses a looped tether element with one or more regions of an expanded diameter to reduce the risk of cutting through the tongue. This region is created to provide a flexible implant with a fixed expanded region, a balloon region or an in-situ expanding region. This method provides a large bearing surface on limited regions of the fiber. Additionally, this method requires a supplemental element to create the expanded region on the fiber. It is anticipated that this type of device will also be difficult to extract from tongue tissues after healing has occurred since the portion buried on the tongue base is larger in cross section than the tracks remaining from the trailing ends of the looped tether.
In spite of the above advances in OSA treatment, there remains a need for devices, systems and methods for treating OSA through minimally invasive approaches that will improve long term results with improved patient compliance and minimized patient discomfort.